1. FIELD OF THE INVENTION
This invention relates to sealant melter/applicator equipment, and more particularly, to sealant melter/applicator equipment energized by an internal combustion engine and having an automatic load switching system for selectively activating either a sealant agitator or a sealant pump.
2. DESCRIPTION OF THE PRIOR ART
A prior art trailer-mounted sealant melter/applicator includes a low cost, low power internal combustion engine which energizes a hydraulic system for continuously driving a reversible, vertically oriented sealant agitator assembly. During the equipment start up phase, the substantially solid, ambient temperature sealant is transformed by heat into high temperature molten sealant. The molten sealant is periodically drained by gravity from a manually actuated valve positioned at the lower rear surface of a vertically oriented sealant tank. A portable sealant dispensing container is periodically refilled from the manually actuated valve on the sealant melter/applicator. This prior art sealant melter/applicator is the predecessor of the present invention.
More sophisticated sealant melter/applicator equipment of the type disclosed in U.S. Pat. No. 4,159,877 utilizes a substantially larger, higher cost two cylinder air cooled engine to energize a hydraulic system having first and second hydraulic pumps coupled in separate hydraulic circuits to independently drive a continuous duty reversible sealant mixing auger and an intermittent duty reversible sealant pump. During sealant application procedures, the sealant pump is continuously activated to dispense molten sealant under pressure through a hose having an end-mounted applicator wand. The discharge of sealant from the applicator wand is controlled by a manual, operator-controlled on/off valve located in the wand. The sealant pump continues to rotate to provide pressurized sealant to the manual on/off valve regardless of the position of that valve.
In this comparatively expensive prior art system, the power output of the internal combustion engine is adequate to enable the sealant mixing auger and the sealant pump to be simultaneously activated without causing engine overloading or stalling.
A substantial price disparity exists between the relatively uncomplicated gravity flow discharge sealant melter/applicator described above and the substantially higher cost, higher performance dual pump hydraulic system sealant melter/applicator disclosed in U.S. Pat. No. 4,159,877.